Testing-mold



H. IV], DAVIS.

TESTING MOLD.

APFLICAHQN FILED SEPT-23,1920.

1,394,255, Patented Oct. 18, 1921,

HELEN M. DAVIS, OF WASHINGTON. DISTRICT OF COLUMBIA.

TESTING-MOLD.

Specification of Letters Patent.

Patented ()ct. 18, 192i.

Application filed September 23, 1920. Serial No. 412,327.

To all w/wm it may concern:

Be it known that I, llnnnN M. DAVIS, a citizen of the United States ofAmerica, and a resident of \Vashington, in the District of Columbia.United States of America, have invented certain new and usefulImprovements in 'lesting-Molds; and I do hereby declare the following tobe a full, clear, and exact description of the invention, such as willenable others skilled in the art to which it appertains to make and usethe same, reference being had to the accompanying drawings, and toletters or figures of reference marked thereon, which form a part ofthis specification.

My invention relates to molds for con 'crete and especially, for moldsof a temporary character, in which to cast standard shapes preferablycylindrical for the purpose of testing of concrete and cement mixtures.

These molds are of standard dimensions, to produce a casting asaccurately as possible, conforming to the requirements of the testingmachine, in which the cast shapes are to be tested. Heretofore thesemolds were made of metal, over size in diameter, longitudinally slit andcompressed by clamps to close the slit and bring the mold to standardsection. After casting the clamps are released, the natural spring ofthe metal opening the mold and releasing it from the casting to permitit to be withdrawn. These molds are heavy and difficult to handle onaccount of their weight and few of them can be conveniently carried on asingle job, such as roadways, bridges, whose concrete mixture oraggregates were to be subjected to tests.

Unslit pasteboard molds have heretofore been tried. These are readilydamaged, extremely bulky, requiring excessive storage space, and notbeing water proof under the existing conditions, absorb moisture fromthe concrete and therefore give improper results, besides, they willstick to the casting after it has set.

I overcome these difficulties by making the molds of thick paper,cardboard or the like, heavily coated with a water proofing substancesuch as paraffin, asphalt varnish, tar, casein glue and similar Waterproofing substances, not decomposable by the lime or basic constituentsof the cement. The coating must have a smooth glossy surface to bepresented to the concrete. The coating not only penetrates the cardboard orpaper but also stands on top of the surface in a continuous evensmooth layer.

The impregnated paper or canlboard customarily has a dull or mattsurface. which will not withstand the hydrostatic pressure and absorbsmoisture from the wet mass, or allow water to leak through, robbing the.casting of moisture and rendering the test inaccurate. In order toprevent this when using parailins, the coating should be done attemperatures near the melting point of the parallins rather than nearthe boiling point so that when the mold is finished there. will be agood glossy coating of parallin standing on the whole interior surface,on the top and bottom edges as well as on the edges of the longitudinalslit. The same is true of other impregnating substances.

Such a surface has the further advantage of enabling the mold to beeasily stripped or torn ofl of the casting leaving a true and accurateshape.

I make these tubular molds with straight sides and symmetrical crosssections, preferably but not necessarily cylinders, the customary sizebeing six inches in diameter and twelve inches high, the smaller size,such as four by eight inches being less in demand.

The cylinders of heavy paper or cardboard, two or three ply, spirallywound or not are slit longitudinally and coated after they are slit, sothat the edges of the slit become well coated and will not absorb water.This will produce edges sufliciently plastic by reason of the coatingthereon to make a joint water tight for most mixtures. The object ofslitting the cylindrical or other symmetrical tubular shapes is topermit them to be nested and shipped or carried nested. From tentotwenty can be nested and carried in a single package. The userconnects or laces the edges of the longitudinal slit, on the job to forma butt joint by stapling the edges together by any suitable wire orsheet metal staples such as are commonly used for fastening papertogether. The staples are set a half inch apart more or less. This willbe sufficient for most cement and concrete mixtures. But in case a verythin mix is to be cast for testing purposes it is well to coat the jointwith paraffin or other Water proofing substance. This can readily bedone with a paraifin any trapped air.

. a standard size.

candle by allowing the drippings therefrom to run over the omt.

In using the mold on the job, a thin layer of neat cement, about aquarter of an inch thick, is placed on a sheet of glass or sheet ironand the laced mold set in this. Then the cement mix or concrete to betested 1s placed in the mold until about three-quarters of the mold isfilled when a stick or wire rod is used to tamp it and eliminate Themold is then filled to the top, struck ofi with a trowel, and a layer ofneat cement placed on the top of the casting and struck off. The testcasting is allowed to set the desired length of time, when the mold istorn 05 or stripped leaving a true cylinder, or other regular shapeready for testing. The mold also forms a protection for the castingduring shipment.

Referring to the drawing in which like parts are similarlydesignated,Figure 1 is a perspective view of a blank made of spirally wound tubelongitudinally slit, and of Fig. 2 is an elevation of the mold afterlacing, and Fig. 3 shows several nested mold blanks.

The slit cylindrical mold blank 4 has its edges 5 brought together in abutt joint and laced by staples 6, the staples extending across theabutting edges 5. lacing one end of a label 7 is laced in place partlyby means of staples 6 joining the abutting edges 5 of the mold, andpartly by one or more additional staples 8 to hold the label against themold and prevent it from being torn off. On this label is placed anydesignation, indicating the particular sample.

In nesting the blanks 4 the outermost blanks are somewhat spread apart,as indicated at 9 while the inner blanks have their edges overlapping asillustrated at 10.

When nested for shipment twenty five cylinders make only slightly morebulk than an ordinary steel mold, such as is used in laboratory work,and weigh only about half as much as a single steel mold. The bulk oftwenty-five of these molds is less than one twentieth the bulk or spacerequired for carrying unslitted paste board molds.

During this I claim- 1. A testing mold blank for cement and concretemixes comprising a longitudinally sl1t paper or pasteboard tubularmold'uniform and symmetrical throughout its length and coated with awater proofing substance, whereby a plurality of such molds may benested.

2. A testingmold for-cement and concrete mixes comprislng alongitudinally slit paper or pasteboard tube, coated with a waterproofin substance, and staple connections connecting the abutting edgesof the slit mold to form a butt joint.

3. A testing mold for cement and concrete mixes, comprising alongitudinally slit paper or pasteboard tube, a water proofing coatingthereon forming a glossy surface over the body and edges of the mold andstaples connecting the abutting edges along the slit.

4. A testing mold for cement and concrete mixes, comprising alongitudinally slit spiral pasteboard tube, a water-proofingcoatingcovering the edges and body of said tube and standing on thesurface thereof, and wire staples connecting the abutting edges of theslit.

5. A cylindrical longitudinally slit spi rally wound multi-plypasteboard tubular mold, having a coating of waterproofing substancestanding on its surface and edges.

6.. A cylindrical, longitudinally slit spirally wound multi-plypasteboard tubular mold having a coating of water proofing substancestanding on its surface and edges, and the edges stapled together toform a butt joint and a label stapled to said mold.

7. A cylindrical, longitudinally slit spirally wound multi-plypasteboard tubular mold having a coating of waterproofing substancestanding on its surface and edges and the edges stapled together to forma HELEN M. DAVIS.

